The harm thesis—the assumption that words harm people—is a defining feature of sexual harassment, hate speech, verbal abuse, and obscene telephone call (OTC) offenses. This thesis ignores the possibility that swearing can be advantageous, cathartic, or an acceptable substitute for physical aggression. Observational data, courtroom evidence and verbal abuse research reviewed here produce conflicting conclusions on the question of harm. The best evidence of harm resides in harassment and OTC studies, but verbal abuse research is indeterminate because of flawed research methodology. Public swearing research reveals that swearing is a common conversational practice resulting in no obvious harm. Common sense (folk psychology) views of swearing are mistaken and inadequate for some decisions regarding harm. Meanwhile, efforts to restrict speech in media and instructional settings continue, despite the lack of a convincing need to do so. Harm from offensive speech is contextually determined; therefore attempts to restrict speech on a universal basis are misguided. Psychologists’ research needs to be informed by public policy and courtroom practices, and public policy and litigation need to be better informed by psychologists’ research.